What does OSHA require on a construction site?
The governing rule is 29 CFR 1926.51, the construction sanitation standard. It requires employers to provide toilet facilities that are both adequate in number and readily accessible, and it sets the minimum by crew size.
| Crew size | Minimum required |
|---|---|
| 20 or fewer | 1 toilet facility |
| 20 or more employees | 1 toilet seat and 1 urinal per 40 workers |
| 200 or more employees | 1 toilet seat and 1 urinal per 50 workers |
What does that look like on a real crew?
- A 12-person framing crew: one unit meets the minimum. Add a second if the site is spread out enough that walking time becomes a real cost.
- A 45-person site: two toilet seats and two urinals, because 45 workers crosses into the second bracket at one per 40.
- A 220-person site: at one per 50 that is five seats and five urinals, fewer than the 40-worker ratio would suggest, because the bracket changes at 200.
- A 30-person mine crew on continuous rotation: the OSHA minimum is one seat and one urinal, but continuous shifts fill units far faster than a single day shift of the same headcount, so service frequency matters more than unit count.
Getting this wrong costs money in both directions. Too few units and the site is out of compliance during an inspection. Too many and you are paying weekly for capacity nobody uses.
How do you size an event?
Event sizing has no federal standard equivalent to 1926.51, and the rules of thumb in wide circulation vary enough that publishing a specific ratio table without naming its source would be guesswork dressed as guidance. What is reliable are the variables, and they matter more than any single ratio.
- Guest count and how long they are on site. A four-hour event and a ten-hour event are different problems at the same headcount.
- Whether alcohol is served, which roughly doubles usage.
- Whether the event is ticketed with a fixed audience, or has people coming and going.
- ADA requirement. Accessible units are a separate count, not a substitution.
- Handwashing provision, which health authorities commonly require near the toilets and away from food service.
- Overnight or multi-day running, which needs servicing built into the schedule rather than bolted on.
What goes wrong when sites get this wrong?
- Sizing to the OSHA floor and treating it as sufficient rather than as a legal minimum.
- Counting an unserviced unit toward the requirement.
- Ignoring shift pattern. Continuous rotation fills units faster than headcount alone predicts.
- Placing units where the service truck cannot reach them by week three, once material is staged.
- Forgetting that alcohol roughly doubles event usage.
- Booking a peak summer weekend late, when regional inventory is already committed.